1. Field of the Invention
The invention relates to a method of manufacturing, and apparatus for use in manufacturing a color conversion filter that enables multicolor display. The color conversion filter can be used, for example, for the display provided by image sensors, personal computers, word processors, TV receivers, facsimile machines, audio apparatus, video apparatus, car navigation apparatus, desktop calculators, telephones, portable terminals, industrial measuring instruments, and related devices.
2. Background Art
In recent years, as one method for realizing multicolor or full-color display devices, a color conversion method has been studied that employs, as filters, color conversion coloring matter (or material) that absorbs near ultraviolet light, blue light, bluish green light, or white light and emits light in visible ranges through wavelength profile conversion. See, for example, Japanese Patent Publications JP-A-8-279394 and JP-A-8-2860331. Employment of the color conversion method makes it possible to increase the degree of freedom in light source selection, because the light source emission color is not limited to white. For example, green light and red light can be obtained through wavelength profile conversion by using a blue organic EL light-emitting device. Therefore, more efficient light sources can be used. A feasibility study has been made of a full-color emission-type display device using a weak energy beam such as near ultraviolet light or visible light, as is described in Japanese Patent Publication JP-A-9-804343).
In addition to realization of a high-resolution color display function and long-term stability of characteristics including the color reproducibility, provision of color conversion filters having high color conversion efficiency is an important issue for the practical use of color display devices. However, if the density of a color conversion coloring material is made higher in order to increase the color conversion efficiency, problems occur such as reduced efficiency due to what is called density extinction and decomposition with age of the color conversion coloring matter. Therefore, the current situation is such that desired color conversion efficiency is obtained by increasing the thickness of a color conversion layer including color conversion coloring matter. To prevent the density extinction and the decomposition of color conversion coloring matter, introducing a bulky substituent into a coloring matter nucleus has been studied (see Japanese Patent Publications JP-A-11-279426, JP-A-2000-44824 and JP-A-2001-164245). To prevent the decomposition of color conversion coloring matter, mixing of a quencher also has been studied (see Japanese Patent Publication JP-A-2002-231450).
To increase the resolution of a multicolor or full-color display device that employs the color conversion method, it is necessary to pattern the color conversion layers at a high resolution. However, if patterning should be performed in such a manner that the width of each pattern is smaller than the film thickness, issues such as pattern shape reproducibility and pattern deformation arise in subsequent manufacturing steps. In addition, where patterning is performed by ordinary photolithography, a coating step, an exposure step including mask registration, and a development step are needed to obtain a color conversion layer of each color. For example, to manufacture a full-color display device which has at least red, green, and blue color conversion layers, a complicated manufacturing process consisting of a large number of steps is required.